Smoke generating compositions and method of use thereof



ABSTRACT OF THE DISCLOSURE A smoke agent consisting essentially of an aluminum alkyl, an aromatic substance having 2 to 3 fused carbocyclic aromatic six-membered rings and from to carbon atoms, said aromatic substance being composed solely of carbon and hydrogen, and a petroleum oil. Smoke is produced by exposing the smoke agent to the atmosphere. An ether having 2 to 3 ether oxygen atoms, up to 20 carbon atoms, and no carbon to carbon unsaturation is preferably included as a flame suppressant.

This invention relates to agents which produce smoke. More specifically, it relates to smoke-producing agents containing an organometallic compound. In a highly preferred embodiment this invention relates to smoke-producing formulations which contain one or more organo aluminum compounds.

Smokes have been employed in many applications. For example, smokes have been employed for marking, signaling and screening, as well as the protection of plants such as citrus trees from frost. They have also been employed in law enforcement actions such as quelling riots, insurgencies, revolutions and the like. In addition, smokes have many military applications, for example, obscuring troop, vehicle or ship maneuvers.

Many of the smoke-producing formulaitons proposed in the past have serious deficiencies. For example, they may be too expensive. Similarly, many smokes produced by prior art smoke agents are toxic, corrosive or irritating to the skin. Thus, in many instances personnel anticipating contact with smoke must wear protective clothing and use a breathing apparatus to obviate untoward effects produced by the smokes. Such protective measures are costly, reduce personnel efliciency and present logistic problems.

For certain operations by the armed forces, law enforcement agencies and the like, non-irritant, non-toxic and non-flammable obscuring smokes are desired. In fact, such relatively harmless smokes are urgently needed for many applications. For example, in law enforcement activities, according to the laws of some governments, in-

dividual rights may be violated if hazardous smoke is employed in some peace-restoring actions. Furthermore, in war-time activities, the use of hazardous smokes is frowned upon in many instances since their use may violate conventions concerning the conduct of warfare. Furthermore, in some military tactical operations, the use of hazardous smokes is precluded where it is desirable to minimize civilian casualties.

To avoid or minimize the deleterious consequences arising from the use of hazardous smokes, prior workers have proposed that smokes be generated from petroleum oils using heat sources such as turbine engines, diesel and spark ignition internal combustion engines, and the like. Moreover, fog-producing devices using oils or water with chemical agents have been suggested. In all of these instances bulky, complex equipment is required which presents logistic problems and renders these methods practically useless in certain instances, for example, in aerial and jungle operations.

nited States Patent Smoke-producing agents commonly employed today, e.g., FS (sulfur trioxide-chlorosulfonic acid) and FM (titanium tetrachloride), which depend upon the reaction of the moisture in the atmosphere, vary markedly in efliciency depending up on the humidity of the atmosphere at the locus of use. The smoke formulations provided by this invention do not depend solely upon a reaction with atmospheric moisture but rather, to a large extent, upon the presence of atmospheric oxygen. Hence, the agents of this invention do not vary so widely in efiiciency and quantity of smoke produced as do the above named and designated prior art formulations. However, the smokeproducing formulations of this invention can produce smoke by reacting with water or oxygen. This is an important feature of this invention.

An object of this invention is to provide smoke-producing agents which do not have many of the deficiencies of the prior art smoke-producing agent and/ or methods. A further object is to provide non-irritant, non-toxic and non-flammable obscuring smokes. Additional objects will be apparent from the following detailed description and appended claims.

The objects of this invention are accomplished by providing smoke-producing formulations containing a metal compound of the types defined hereinbelow.

Essentially the smoke formulations of this invention comprise an organometallic compound and one or more diluents and/or flame suppressants to control the rate of oxidation and/ or hydrolysis :of the organometallic compound. In a preferred embodiment the smoke formulations of this invention comprise an organometallic compound, an aromatic substance and a petroleum oil. In a very highly preferred embodiment this invention provides a smoke agent consisting essentially of:

(A) an aluminum alkyl having the formula R Al wherein R is an organic radical having up to six carbon atoms, said radical being selected from alkyl or aryl groups, and X is a halogen such as chlorine or bromine. Most preferably, y has a value of 0-3. in addition,

aluminum compounds having the formula RZAIH can also be employed. In this formula, -R has the same significance as above. A very highly preferred type of aluminum compounds has the formula 'R Al wherein R is an alkyl or aryl group having up to about 6 carbon atoms. (These compounds have the above formula R Al X where y=0.) Most preferably, R is an alkyl group having up to 6 carbon atoms which is solely composed of carbon and hydrogen.

In addition to the aluminum compounds formulated above boron compounds having the formula wherein R has the same significance as defined above can also be used.

Highly preferred organometallic compounds employed in this invention include tripropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-amylaluminum, trisec-amylaluminum, tri-n-hexylaluminum, and the like. A most highly preferred aluminum alkyl is triethylaluminum.

All the organic radicals bonded to the metal atom or atoms (in the organometallic compounds employed inthis invention) need -not be identical. For example, two or three different radicals can be bondedto aluminum. Compounds of this type are illustrated by dimethyl ethyl aluminum, diethyl methyl aluminum, methyl diisopropyl aluminum, methyLhexyl butyl aluminum and the like. Thus, the triorgano aluminum compounds applicable inthis invention include compounds having the formula RRRAl wherein R, R and R" are alike or different alkyl radicals of one to six carbon atoms.

In addition to one or more of the metallic compounds noted above, preferred formulations of this invention also contain an aromatic compound. Applicable aromatic materials are those which have from 2 to 3 fused carbocyclic aromatic six-membered rings. Preferably, these compounds are solely composed of a carbon and hydrogen and most preferably they also contain from to about 20 carbon atoms. Preferred substances of this type have up to 20 carbon atoms and are selected from the class consisting of naphthalene, alkyl substituted naphthalenes, acenaphthene, alkyl substituted acenaphthenes, fiuorene, alkyl substituted fluorenes, phenanthrene, alkyl substituted phenanthrenes, anthracene and alkyl substituted anthracenes. Of these compounds, naphthalene and the alkyl substituted naphthalenes are preferred. Highly preferred alkyl naphthalenes are amethylnaphthalene, a-ethylnaphthalene and fi-methyb naphthalene. A very highly preferred aromatic substance is a-methylnaphthalene.

The third major ingredient in the preferred formulations of this' invention is a petroleum oil. In general, any petroleum oil of high flash point can be employed. A preferred oil is mineral oil such as U.S.P. white mineral oil. A very highly preferred oil is Neutral No. 75 .oil which is a distilled solvent-refined, dewaxed petroleum oil having a viscosity in Saybolt Universal seconds at 100 F. within the range from about 70 to 80. Usually oils of this type have a viscosity in Saybolt Universal seconds within the range from 72 to 78.

In addition to the petroleum oils described above, other petroleum fractions can also be employed. For example, ordinary heating oils, disel oil and kerosene may be used. Similarly, crude petroluem can be employed. One or more of the above diluents can be used. For example, crude petroleum-kerosene mixtures are applicable as well as mixtures of home heating oils and kerosene.

In general, the smoke formulations of this invention contain from about to about 80 parts by weight of one or more organometallic compounds, from about 5 to about 50 parts. of an aromatic substanceof the type described above and from about 10 to about 90 parts of petroleum or petroleum-derived products (all parts are by weight). The preferred trialkyl aluminum formulations of this invention'contain from about 40 to about 60 parts by weight of one or more trialkyl aluminums, from about 10 to about parts by weight of one or more aromatic substances of the type described 'i .4 above and from about 40 to about parts of a petroleum lubricating oil.

In addition to the above named ingredients the formulations of this invention may optionally contain minor amounts, say about up to 10, percent by weight, of additives to prevent freezing, reduce flame hazards, improve solubilities or compatibilities, etc. Thus, the formulations of this invention may contain fluorocarbons, silicones, dispersants, detergents, as well asoxidizing salts such as ammonium nitrate, permanganates,' chlorates, perchlorates, etc; In addition, the compositions of this invention may optionally containmetal alcoholates such as tetraisopropyl titanate (titanium tetraisopropylate), tetran-butyl titanate, and the like.

'Ethers are a preferred type of additionalingredient which may op tionally be included in the smoke-producing formulations of this invention. In general, from about 5 to about 90 parts of weight of an ether may be included in the formulations. Like the aromatic substances discussed above the ethers seem to have a flame suppressant effect.

The preferred ethers are polyethers; in other words, they contain two or more ether oxygen atoms. Preferred polyethers are the diethers and triethers (ethers containing 2 and 3 ether oxygen atoms, respectively) having up to about 20 carbon atoms.

The biethers which are applicable herein are represented by the formula In this formula R is a bridging group, that is, an alkylene radical of a branched or (preferably) a straight chain containing from 1 to about 6 carbon atoms. In addition, the bridging R group may be a cycloalkyl group, that is, it may be a saturated ring containing from 4 to 6 carbon atoms. In the above formula, R is a terminal group which maybe a saturated, straight or branched chain alkyl group containing from 1 to 20 carbon atoms. In addition, R can also be a saturated alicyclic group, that is, it may be an alicyclic rin'g radical containing from 4 to 6 carbon atoms. R", like R, is a terminal group. Hence, it is selected from the same type of radicals as R. Preferably R and R are identical radicals. Most preferably they are alkyl radicals having from l'to 4 carbon atoms. Illustrative but non-limitingexamples of biethers which'are applicable in this invention include dimethoxyethane, 'diethoxyethane, di'butoxyethane, and the like.

The most preferable polyethers are the triethers represented by the following formula:

In this formula, R, R and R have the same significance as that in the above formula which illustrates the biethers. Illustrative but non-limiting examples of triethers which are applicable in this invention include dipropylene glycol diethylether, dibutylene glycol dimethylether, dipropylene glycol dibutylether, dihexylene glycol diisopropylether, dihexylene glycol dibutylether, and the like. Very highly preferred triethers are diethlene glycol dimethylether and diethylene glycol dibutylether.

The formulations of this invention can be prepared in any convenient manner. It is onlynecessary to mix the desired ingredients in the desiredamounts. In many instaces, it is preferable to mix the ingredients under a blanket of an inert atmosphere. Many inert gases can be employed to supply the inert atmosphere, e.g., nitrogen,

. neon, argon, and the like. Because of its low cost and formulations of this invention and are non-limiting. All parts are by weight unless otherwise noted.

EXAMPLE I Parts Triethylaluminum 40 a-Methylnaphthalene 12.4 Neutral No. 75 oil 47.6

This formulation is activated by oxygen and/or moisture in the air to produce a dense white smoke. The formulation is a clear mobile liquid at temperatures above F. The above formulation is chemically stable under storage conditions of F. to 120 F. The density of the material is about 0.85 gram per ml.

The following table lists other smoke formulations of this invention. In the table the various abbreviations have the following meanings.

TEA-Triethylaluminum DEZDiethylzinc DMC-Diethylene glycol dimethyl ether NAP-Naphthalene a-NAP--ot-Methylnaphthalene 35 oilU.S.P. white mineral oil 75 oilNeutral No. 75 oil DBC-Diethylene glycol dibutyl ether TIBA-Triisobutyl aluminum TABLE i 6. the following ingredients under nitrogen in the amounts stated:

Parts Triisobutylaluminum 80 White mineral oil 20 Anthracene 5 Similar formulations are prepared by substitution of methyl diethylaluminum, methyl dibutylaluminum, ethyl dihexylaluminum, methyl isopropyl butlaluminum or methl amyl isohexylaluminurn for the aluminum compounds called for in Examples I-XXIII.

Similar results are obtained if l-methylanthracene, 3- ethylanthracene or S-isobutylanthracene are substituted for the anthracene employed in the previous formulations.

EXAMPLE XXIV A smoke-producing formulation is prepared by mixing the following ingredients under nitrogen in the amounts stated:

I Parts Tri-n-propylaluminum Diethylene glycol dimethylether 20 Phenanthrene 5 Similar results are obtained if S-n-heptylphenanthrene is substituted for the phenanthrene employed in the previous DEZ NAP 35 Oil 75 Oil TIBA 52.0.

EXAMPLE XX A smoke-producing formulation is prepared by mixing the following ingredients in the amounts stated under nitrogen:

Parts Trimethylaluminum 75 Diethylene glycol dimethylether 15 Neutral No. 75 oil l0 EXAMPLE XXI A smoke-producing formulation is prepared by mixing the following ingredients in the amounts stated under nitrogen:

Parts Trimethylaluminum -Q 15 a-Methylnaphthalene 25 Diethylene glycol dimethylether 5 EXAMPLE XXII A smoke-producing formulation is prepared by mixing the following ingredients in the amounts stated under nitrogen:

EXAMPLE XXIII A smoke-producing formulation is prepared by mixing example. Similar preparations are made by substituting dibutoxyethane, dipropoxybutane, dicyclohexyloxyethane, diethylene glycol dibutyl ether, diethylene glycol dipropyl ether, diethylene glycol dihexyl ether, or dibutylene glycol dihexyl ether for the dimethylene glycol dimethyl ether employed in the previous formulations.

EXAMPLE XXV A smoke-producing formulation is prepared by mixing the following ingredients under nitrogen in the amounts stated:

Parts Trimethylaluminum 10' White mineral oil 90 Fluorene 5 Similar preparations are prepared by substituting 4-heptyl fluorine, fi-rnethylnaphthalene, 1,5-dimethylnaphthalene, 1,6-dipentylnaphthalene or S-butylacetnaphthene for the fiuorene employed in the above formulations.

The smoke-formulations of this invention produce a relatively innocuous smoke. The solid and liquid particles within the smoke are most probably the oxides of the metals within the organometallic compounds, or hydrated metal oxides, as well as the components within the diluents and flame suppressants, e.g., Neutral No. oil and m-methylnaphthalene, respectively. Gaseous products which are likely to be included in the smokes produced by this invention are ethylene, butylene, butane, hydrogen ethane, carbon dioxide and carbon monoxide, all at very 7 low concentrations. It is anticipated that the hydrocarbon diluents should be innocuous in the exposure time and concentration range time likely to be encountered. The metal oxides within the smokes, e.g. aluminum oxide, are generally considered to be relatively non-toxic.

This invention is extended to cover smoke-producing formulations which contain hydrides such as boron hydrides. Furthermore, colored smokes may be attained by incorporating organometallic compounds, particularly of the pi-bonded type, whose metals form colored oxides.

Having fully described the novel compositions of this invention, their method of preparation and their use, it is desired that this invention be limited only within the lawful scope of the appended claims.

We claim:

1. A smoke agent consisting essentially of (A) from about 15 to about 80 parts by weight of an aluminum alkyl having the formula RR'R"A1 wherein R, R and R" .are radicals solely composed of carbon and hydrogen and having up to 6- carbon atoms,

(B) from about to about 50 parts by weight of an aromatic substance having 2 to 3 fused carbocyclic aromatic six-membered rings and from to carbon atoms, said aromatic substance being solely composed of carbon and hydrogen,

(C) from about 10 to about 90 parts by weight of a petroleum oil, and

(D) from about 5 to about 90 parts by weight of an ether having two to three ether oxygen atoms, up to 20 carbon atoms and no carbon to carbon unsaturation.

2. A smoke agent consisting essnetially of (A) from about 40 to about 60 parts by Weight of an aluminum alkyl having the formula wherein R is an alkyl radical solely composed of carbon and hydrogen and having up to 6 carbon atoms,

(B) from about 10 to about 20 parts by weight of an aromatic substance having 2 to 3 fused carbocyclic, aromatic, six-membered rings and from 10 to 20 carbon atoms, said aromatic substance being solely composed of carbon and hydrogen, and

(C) from about 40 to about 60 parts by weight of a petroleum oil.

3. A smoke agent consisting essentially of (A) from about 40 to about 60 parts of triethylaluminum,

(B) from about 10 to about 20 parts of an aromatic substance having 2 to 3 fused carbocyclic, aromatic, six-membered rings and from 10 to 20 carbon atoms, said aromatic substance being solely composed of carbon and hydrogen, and

(C) from about 40 to about 60 parts of a petroleum oil.

4. A smoke agent consisting essentially of (A) from about 40 to about 60 parts by weight of an aluminum alkyl having the formula wherein R is an alkyl radical solely composed of carbon and hydrogen and having up to 6 carbon atoms,

(B) from about 10 to about 20 parts of an aromatic substance having up to 20 carbon atoms selected from the class consisting of naphthalene, alkyl substituted naphthalenes,acenaphthene, alkyl substituted acenaphthenes, fluorene, alkyl substituted fluorenes, phenanthrene, alkyl substituted phenanthrenes, anthracene and alkyl substituted anthracenes, and

(C) from about40 to about 60 parts of a petroleum oil.

5. A smoke agent of claim 4 wherein said aromatic substance is a-methylnaphthalene.

6. A smoke agent of claim 5 wherein said aluminum alkyl is triethylaluminum. Y

7. A smoke agent of claim 5 wherein said trialkyl aluminum is triisobutylaluminum.

8. A smoke agent of claim 5 wherein said aluminum alkyl is tri-n-butylaluminum.

9. A smoke agent of claim 5 wherein said petroleum oil is a distilled, solvent refined, dewaxed, petroleum oil having a viscosity in Saybolt Universal seconds at 100 F. within the range of from about to 80.

10. A smoke agent consisting of 40 weight percent of triethylaluminum, 12.4 weight percent of a-methylnaphthalene and 47.6 percent of a distilled solvent-refined, dewaxed petroleum oil having a viscosity in Saybolt Universal seconds at 100 F. within the range of from 72 to 78.

11. A process for producing smoke, said process comprising exposing to the atmosphere a smoke agent consisting essentially of (A) from about 15 to about parts by weight of an aluminum alkyl having the formula wherein R is an alkyl radical solely composed of carbon and hydrogen and having up to 6 carbon atoms,

(B) from about 5 to about 50 parts by weight of an aromatic substance having 2 to 3 fused carbocyclic aromatic six-membered rings and from 10 to 20 carbon atoms, said aromatic substance being solely composed of carbon and hydrogen, and

(C) from about 10 to about parts by weight of a petroleum oil.

12. Method for producing a smoke, said method comprising exposing to the atmosphere a smoke agent consisting of 40 weight percent of triethylaluminum, 12.4 weight percent of u-methyl naphthalene and 47.6 percent of a distilled solvent-refined, dewaxed petroleum oil having a viscosity in Saybolt Universal seconds at F. within the range of from 72 to 78.

References Cited UNITED STATES PATENTS 2,432,577 12/ 1947 Levey et al. 252305 2,936,291 5/1960 Peters et al. 252431 3,113,986 12/1963 Breslow et al. 252-431 X 3,309,268 3/1967 Sherman 252-305 X LEON D. ROSDOL, Primary Examiner.

RICHARD D. LOVERING, Assistant Examiner. 

